U.S. patent application number 14/049965 was filed with the patent office on 2015-04-09 for hearing assistance coplanar waveguide.
This patent application is currently assigned to Starkey Laboratories, Inc.. The applicant listed for this patent is Stephen Paul Flood, Jay Rabel. Invention is credited to Stephen Paul Flood, Jay Rabel.
Application Number | 20150098599 14/049965 |
Document ID | / |
Family ID | 51661991 |
Filed Date | 2015-04-09 |
United States Patent
Application |
20150098599 |
Kind Code |
A1 |
Flood; Stephen Paul ; et
al. |
April 9, 2015 |
HEARING ASSISTANCE COPLANAR WAVEGUIDE
Abstract
Disclosed herein, among other things, are methods and
apparatuses that provide a manufacturable RF transmission line to
go through the bend area of a flexible circuit to be used in a
compact design, such as in a compact hearing aid design. One aspect
of the present subject matter relates to using multiple inner
layers of the flexible circuit to route RF transmission. By not
using outer layers, the RF transmission line will be less
susceptible to delamination from the polyimide dielectric layer.
One aspect of the present subject matter relates to choosing copper
transmission line to have dimensions that allow for narrower
transmission lines with good RF return loss. The copper
transmission line dimensions also allow for manufacturing in a
standard process without adding extra cost.
Inventors: |
Flood; Stephen Paul; (Eden
Prairie, MN) ; Rabel; Jay; (Shorewood, MN) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Flood; Stephen Paul
Rabel; Jay |
Eden Prairie
Shorewood |
MN
MN |
US
US |
|
|
Assignee: |
Starkey Laboratories, Inc.
Eden Prairie
MN
|
Family ID: |
51661991 |
Appl. No.: |
14/049965 |
Filed: |
October 9, 2013 |
Current U.S.
Class: |
381/315 ;
333/238 |
Current CPC
Class: |
H04R 2225/51 20130101;
H04R 2225/59 20130101; H04R 25/554 20130101; H04R 25/48 20130101;
H04R 25/55 20130101; H01P 3/003 20130101 |
Class at
Publication: |
381/315 ;
333/238 |
International
Class: |
H04R 25/00 20060101
H04R025/00; H01P 3/00 20060101 H01P003/00 |
Claims
1. A hearing assistance coplanar waveguide comprising: a first
ground conductor disposed on a first side of a first dielectric; a
first conductor disposed on the first side of the first dielectric,
wherein the first ground conductor and the first conductor are
separated by a first gap; a second ground conductor disposed on the
first side of the first dielectric, wherein the second ground
conductor and the first conductor are separated by a second gap; a
third ground conductor disposed on a second side of the first
dielectric; a second conductor disposed on the second side of the
first dielectric, wherein the third ground conductor and the second
conductor are separated by a third gap; and a fourth ground
conductor disposed on the second side of the first dielectric,
wherein the fourth ground conductor and the second conductor are
separated by a fourth gap.
2. The hearing assistance coplanar waveguide of claim 1, further
comprising a second dielectric, wherein: the second dielectric is
disposed on the first ground conductor, first gap, first conductor,
second gap, and second ground conductor; the second dielectric
extends into the first and second gap; and at least a portion of
the second dielectric contacts at least a portion of the first side
of the first dielectric.
3. The hearing assistance coplanar waveguide of claim 1, further
comprising a third dielectric, wherein: the third dielectric is
disposed on the third ground conductor, second conductor, and
fourth ground conductor; the third dielectric extends into the
third and fourth gap; and at least a portion of the third
dielectric contacts at least a portion of the second side of the
first dielectric.
4. The hearing assistance coplanar waveguide of claim 3, wherein:
the first dielectric includes a first dielectric material; and the
second and third dielectrics include a second dielectric material,
wherein the first dielectric material is different from the second
dielectric material.
5. The hearing assistance coplanar waveguide of claim 3, wherein
the first, second, and third dielectric layers include a
polyimide.
6. The hearing assistance coplanar waveguide of claim 5, wherein
the polyimide includes an adhesive.
7. The hearing assistance coplanar waveguide of claim 3, wherein
the at least one of the first, second, third, or fourth gaps is
arranged according to the wavelength of the intended transmission
frequency.
8. The hearing assistance coplanar waveguide of claim 3, wherein
the dimensions of at least one dielectric is arranged to reduce
signal degradation due to higher harmonics.
9. The hearing assistance coplanar waveguide of claim 3, wherein
the first, second, third, and fourth ground conductors are
electrically coupled.
10. The hearing assistance coplanar waveguide of claim 3, wherein
conductor 1 and conductor 2 are electrically coupled.
11. A hearing assistance device comprising: a radio frequency
driver component; a coplanar waveguide coupled to the radio
frequency driver component; and an antenna coupled to the coplanar
waveguide.
12. The hearing assistance device of claim 11, further comprising
an impedance matching filter coupled to the radio frequency driver
component and to the coplanar waveguide.
13. The hearing assistance device of claim 11, wherein the radio
frequency driver component includes an impedance matching
filter.
14. The hearing assistance device of claim 11, further comprising
an impedance matching filter coupled to the coplanar waveguide and
to the antenna.
15. The hearing assistance device of claim 11, further comprising a
standing acoustic wave filter coupled to the coplanar waveguide and
to the antenna.
16. The hearing assistance device of claim 11, further comprising a
signal processing component coupled to the radio frequency driver
component.
17. The hearing assistance device of claim 16, further comprising a
microphone coupled to the signal processing component.
18. The hearing assistance device of claim 16, further comprising
an amplifier coupled to the signal processing component.
19. The hearing assistance device of claim 16, further comprising a
speaker coupled to the amplifier.
20. A hearing assistance system, the system comprising: a radio
frequency driver component; an antenna; and a waveguide means for
propagating a radio frequency signal from the radio frequency
driver component to the antenna.
21. The hearing assistance system of claim 20, wherein the
waveguide means is a coplanar waveguide.
22. The hearing assistance system of claim 20, further comprising
an impedance matching filter coupled to the radio frequency driver
component and to the waveguide means.
23. The hearing assistance device of claim 20, further comprising a
standing acoustic wave filter coupled to the waveguide means and to
the antenna.
24. The hearing assistance device of claim 20, further comprising a
signal processing component coupled to the radio frequency driver
component.
Description
FIELD OF THE INVENTION
[0001] The present subject matter relates generally to hearing
assistance devices, and in particular to waveguides for hearing
assistance devices.
BACKGROUND
[0002] Modern hearing assistance devices, such as hearing aids, are
electronic instruments worn in or around the ear that compensate
for hearing losses by specially amplifying sound. Hearing aids
typically include electronic components mounted on or attached to
printed circuit boards to enhance the wearer's listening
experience.
[0003] To accommodate the relatively small hearing aid form factor,
hearing aid radio frequency (RF) transmission lines may be
implemented on flexible circuit boards. However, the performance of
RF transmission lines is limited when using flexible circuit
boards, especially in areas of the flexible circuit boards that are
bent to accommodate the hearing aid form factor.
[0004] In order to provide a manufacturable RF transmission line
for a flexible circuit bend area that provides improved RF
performance, existing solutions use microstrip or stripline
configurations. These microstrip or stripline configurations may
use external layers. However, these microstrip or stripline exhibit
excessively narrow transmission lines. Such excessively narrow
transmission lines are difficult to manufacture, as the
manufacturing tolerance variations tend to exceed the requirements
of the narrow transmission lines. Additionally, microstrip or
stripline antennas using the external layers of the flexible
circuit would have problems with delamination of the copper from
the flexible circuit polyimide layer.
[0005] Some existing coplanar waveguides include methods of
constructing coplanar waveguides on semi-rigid boards. These are a
combination regular circuit board and flexible circuit board. Other
existing coplanar waveguides include an air gap within the coplanar
waveguide.
[0006] What is needed in the art is an improved system that
provides a manufacturable RF transmission line for a flexible
circuit bend area that provides improved RF performance.
SUMMARY
[0007] Disclosed herein, among other things, are methods and
apparatuses that provide a manufacturable RF transmission line to
go through the bend area of a flexible circuit to be used in a
compact design, such as in a compact hearing aid design.
[0008] One aspect of the present subject matter relates to using
multiple inner layers of the flexible circuit to route RF
transmission. By not using outer layers, the RF transmission line
will be less susceptible to delamination from the polyimide
dielectric layer. One aspect of the present subject matter relates
to selecting copper transmission line dimensions that can withstand
manufacturing tolerance variations. The copper transmission line
dimensions also allow for manufacturing in a standard process
without adding extra cost. Other aspects are provided without
departing from the scope of the present subject matter.
[0009] This Summary is an overview of some of the teachings of the
present application and not intended to be an exclusive or
exhaustive treatment of the present subject matter. Further details
about the present subject matter are found in the detailed
description and appended claims. The scope of the present invention
is defined by the appended claims and their legal equivalents.
BRIEF DESCRIPTION OF THE DRAWINGS
[0010] FIG. 1 shows a circuit diagram of a hybrid circuit
configured for use in a hearing aid, according to one embodiment of
the present subject matter.
[0011] FIG. 2 shows a circuit diagram of a hybrid circuit with
integrated match filter configured for use in a hearing aid,
according to one embodiment of the present subject matter.
[0012] FIG. 3 shows a perspective diagram of a coplanar waveguide
according to one embodiment of the present subject matter.
[0013] FIG. 4 shows a diagram of a multiple layer coplanar
waveguide according to one embodiment of the present subject
matter.
DETAILED DESCRIPTION
[0014] Disclosed herein, among other things, are methods and
apparatuses for transmitting radio waves from an RF source to an
antenna, such as in a compact hearing aid design.
[0015] FIG. 1 shows a circuit diagram of an embodiment of a hybrid
circuit 100 configured for use in a hearing aid. Hybrid circuit 100
includes a microphone 105, a signal-processing unit 110, an RF
drive circuit 115, a coplanar waveguide 120, a standing acoustic
wave (SAW) filter 125, a match filter 130, and an antenna 135.
Physically, hybrid circuit 100 can be realized as a single compact
unit having an integrated coplanar waveguide 120.
[0016] Signal processing unit 110 provides the electronic circuitry
for processing received signals from the microphone 105 for
wireless communication between a hearing aid in which hybrid
circuit 100 is configured and a source external to the hearing aid.
The source external to the hearing aid can be used to provide
information transferal for testing and programming of the hearing
aid.
[0017] Signal processing unit 110 may provide processed signals to
the RF drive circuit 115, which may have leads to couple to
coplanar waveguide 120. Because the coplanar waveguide 120 provides
a low-profile transmission line that may be mounted directly on a
circuit board, the coplanar waveguide 120 may be used in compact
designs. Additionally, the coplanar waveguide 120 may provide high
frequency response, as the design of the coplanar waveguide 120
avoids parasitic discontinuities in the ground plane.
[0018] Coplanar waveguide 120 may be coupled to a SAW filter 125 to
use an analog filter to match the complex impedance of the coplanar
waveguide to the impedance of the antenna 135. Complex impedance
may be matched further by coupling the coplanar waveguide 120 and
SAW filter 125 to a match filter 130. Impedance matching may also
be performed within the coplanar waveguide 120 by distributing
impedance matching elements within the coplanar waveguide 120. For
example, the coplanar waveguide 120 may include a matching network
(e.g., inductors, capacitors, etc.) to perform impedance matching.
In some embodiments, the coplanar waveguide 120 may include a
series of waveguides connected through various RLC networks.
[0019] Signal processing unit 110 may also provide the processing
of signals representing sounds, whether received as acoustic
signals or electromagnetic signals. Hybrid circuit 100 may also
include an amplifier 140 and a speaker 145. Signal processing unit
110 provides an output that is increased by amplifier 140 to a
level that allows sounds to be audible to the hearing aid user.
Amplifier 140 may be realized as an integral part of signal
processing unit 110. As can be appreciated by those skilled in the
art upon reading and studying this disclosure, the elements of a
hearing aid housed in a hybrid circuit that includes an integrated
coplanar waveguide can be configured in various formats relative to
each other for operation of the hearing aid.
[0020] The elements of hybrid circuit 100 are implemented in the
layers of hybrid circuit 100 providing a compact circuit for a
hearing aid. In an embodiment, a hearing aid using a hybrid circuit
shown as hybrid circuit 100 is a CIC hearing aid operating at a
frequency suitable for wireless communication exterior to the
hearing aid. In an embodiment, the coplanar waveguide for the CIC
hearing aid is configured in a hybrid circuit as a substrate based
coplanar waveguide. In another embodiment, the coplanar waveguide
for the CIC hearing aid is configured in a hybrid circuit as a flex
coplanar waveguide. The resulting circuit may be designed for a
number of different frequencies, or may be designed to be
relatively frequency independent. For example, in one embodiment,
the circuit is adapted to operate at about 916 MHz. As another
example embodiment, the circuit is adapted to operate at about 900
MHz. Other frequencies of operation are possible, and the ones
stated herein are intended to demonstrate the flexibility of the
circuit design. In various embodiments, the circuit is designed to
be relatively frequency independent, to operate over a range of
frequencies. Therefore, various embodiments of hybrid circuit 100
may operate at different frequencies covering a wide range of
operating frequencies without departing from the present subject
matter.
[0021] FIG. 2 shows a circuit diagram of an embodiment of a hybrid
circuit 200 with integrated match filter configured for use in a
hearing aid. Hybrid circuit 200 includes a microphone 205, a
signal-processing unit 210, an RF drive circuit 215, a match filter
230, a coplanar waveguide 220, and an antenna 235. The RF drive
circuit 215 may be manufactured to include the match filter 230 to
enable a compact design. Hybrid circuit 200 may also include an
amplifier 240 and a speaker 245 to provide for processing of
signals representing sounds.
[0022] FIG. 3 shows a perspective diagram of a coplanar waveguide
300. One layer of the coplanar waveguide 300 may include a first
ground conductor 305 (e.g., ground trace), a conductor 310, and a
second ground conductor 315. The first ground conductor 305 and the
conductor 310 may be separated by a first gap 320, and the
conductor 310 and the second ground conductor 315 may be separated
by a second gap 325. The conductor 310 and the first and second
ground conductors 305 and 315 may be affixed to a dielectric 330.
The coplanar waveguide 300 may include an optional third ground
conductor 335, where the optional third ground conductor 335 may be
affixed to the side of the dielectric 330 opposite from the
conductor 310 and the first and second ground conductors 305 and
315. In some embodiments, a second dielectric may be arranged on
the first and second ground conductors 305 and 315 and on the
conductor 310. The second dielectric may fill the first and second
gaps 320 and 325.
[0023] If the coplanar waveguide is limited to a single layer,
manufacturing tolerances may vary excessively, degrading return
loss below the desired performance level. With the coplanar
waveguide implemented on the two layers, however, the return loss
performance may increase from approximately 10 dB to greater than
30 dB, such as is shown in FIG. 4.
[0024] FIG. 4 shows a diagram of a multiple layer coplanar
waveguide 400. One layer of the multiple layer coplanar waveguide
400 may include a first ground conductor 405, a first conductor
410, and a second ground conductor 415. The first ground conductor
405 and the first conductor 410 may be separated by a first gap
420, and the first conductor 410 and the second ground conductor
415 may be separated by a second gap 425. The first conductor 410
and the first and second ground conductors 405 and 415 may be
affixed to a second dielectric 430, and the second dielectric 430
may fill the first and second gaps 420 and 425. The first conductor
410, first and second ground conductors 405 and 415, and second
dielectric 430 may be affixed to a first dielectric 435. The first
dielectric 435 may be affixed to a third ground conductor 445, a
second conductor 450, and a fourth ground conductor 455. The third
ground conductor 445 and the second conductor 450 may be separated
by a third gap 460, and the second conductor 450 and the fourth
ground conductor 455 may be separated by a fourth gap 465. The
second conductor 450 and the third and fourth ground conductors 445
and 455 may be affixed to a third dielectric 440, and the third
dielectric 440 may fill the third and fourth gaps 460 and 465. The
arrangement of second dielectric 430, first and second ground
conductors 405 and 415, first conductor 410, and first and second
gaps 420 and 425 may form a first coplanar waveguide layer 470.
Similarly, the arrangement of third dielectric 440, third and
fourth ground conductors 445 and 455, second conductor 450, and
third and fourth gaps 460 and 465 may form a second coplanar
waveguide layer 475. In various embodiments, additional layers of
coplanar waveguide layers may be formed on the first or second
coplanar waveguide layers 470 and 475.
[0025] The ground conductors 405, 415, 445, and 455 may be mutually
electrically coupled. For example, first and second ground
conductors 405 and 415 may be physically connected, such as forming
a U-shape. The first and second ground conductors 405 and 415 may
be electrically coupled to the third and fourth ground conductors
445 and 455 using an electrically conductive via (e.g., a buried
via) through the first dielectric 435. The ground conductors 405,
415, 445, and 455 may be electrically coupled using wires or other
means.
[0026] The first conductor 410 and second conductor 450 may be
mutually electrically coupled. For example, first and second
conductors 410 and 450 may be physically connected at the beginning
and end of the line. The first and second conductors 410 and 450
may be electrically coupled using an electrically conductive via
(e.g., a buried via) through the first dielectric 435.
[0027] The geometry of the various elements within the multiple
layer coplanar waveguide 400 (e.g., conductor line width, conductor
height, gap width, dielectric height) and dielectric material
selection may determine the characteristic impedance of the first
and second conductors 410 and 450. The geometry of gaps 420, 425,
460, and 465 may be arranged according to the wavelength of the
intended transmission frequency, where the ratio of the line width
to the gaps is adjusted to provide optimum return loss. In some
embodiments, the gaps 420, 425, 460, and 465 may be arranged to
provide proper spacing in the first and second conductors 410 and
450. For example, the first and second conductors 410 and 450 may
be approximately twice as wide as the gaps 420, 425, 460, and 465.
In some embodiments, the gaps 420, 425, 460, and 465 may be
arranged to avoid signal degradation due to higher harmonics. For
example, the gaps 420, 425, 460, and 465 may be arranged at a
spacing of 40 millimeters, which may reduce adverse effects from
fourth or fifth harmonics. The gaps 420, 425, 460, and 465 may be
generated by etching. The gaps 420, 425, 460, and 465 may include a
polyimide layer, where the polyimide may function as an adhesive.
Because of the reduced sensitivity of the line width and gap width
to manufacturing tolerances, the multiple layer coplanar waveguide
400 is able to yield better return loss over manufacturing
tolerances.
[0028] The layers used in FIG. 4 may be implemented in a compact,
flexible circuit design. However, flexible circuit designs are
subject to delamination of outer layers. Existing RF transmission
lines may use micro-strip or stripline within these internal
layers. Within the inner layers of the flexible circuit, the
dielectric thickness may be reduced to 0.001 inch or less. The thin
dielectric layers within microstrip, stripline, and single-layer
CPW, yield narrow line widths. These narrow line widths would be
susceptible to standard manufacturing tolerances for polyimide
flexible circuit technology, resulting in inconsistent
(unit-to-unit) or significantly degraded performance of the
transmission line.
[0029] The layers used in FIG. 4 may be implemented within a
flexible circuit board. By implementing the coplanar waveguide on
inner layers within a flexible circuit board, the multi-layer
design may improve performance of the RF transmission line, while
meeting the design constraints of the flexible circuit design. The
flexible circuit design may be used to allow folding of the circuit
board to fit compactly in a hearing aid design. In various
embodiments, the coplanar waveguide may be used within ceramic
substrate designs and on rigid printed circuit board designs.
Additional layers can be used in various embodiments.
[0030] In some embodiments, the dielectric layers 430, 435, and 440
may be selected to include materials that are lightweight,
flexible, and resistant to heat and chemicals. For example, the
dielectric layers dielectric layers 430, 435, and 440 may be
selected to include one or more polyimides. In some embodiments,
the first and third dielectric layers 430 and 440 include a first
dielectric material, and the first dielectric layer 435 includes a
different dielectric material than the second and third dielectric
layers 430 and 440.
[0031] It is understood that variations in communications circuits,
protocols, antenna configurations, and combinations of components
may be employed without departing from the scope of the present
subject matter. Hearing assistance devices typically include an
enclosure (e.g., housing), a microphone, a speaker, a receiver, and
hearing assistance device electronics including processing
electronics. It is understood that in various embodiments the
receiver is optional. Antenna configurations may vary and may be
included within an enclosure for the electronics or be external to
an enclosure for the electronics. Thus, the examples set forth
herein are intended to be demonstrative and not a limiting or
exhaustive depiction of variations.
[0032] It is further understood that a variety of hearing
assistance devices may be used without departing from the scope and
the devices described herein are intended to demonstrate the
subject matter, but not in a limited, exhaustive, or exclusive
sense. It is also understood that the present subject matter can be
used with devices designed for use in the right ear or the left ear
or both ears of the wearer.
[0033] It is understood that hearing aids typically include a
processor. The processor may be a digital signal processor (DSP),
microprocessor, microcontroller, other digital logic, or
combinations thereof. The processing of signals referenced in this
application can be performed using the processor. Processing may be
done in the digital domain, the analog domain, or combinations
thereof. Processing may be done using subband processing
techniques. Processing may be done with frequency domain or time
domain approaches. Some processing may involve both frequency and
time domain aspects. For brevity, in some examples may omit certain
modules that perform frequency synthesis, frequency analysis,
analog-to-digital conversion, digital-to-analog conversion,
amplification, and certain types of filtering and processing. In
various embodiments, the processor is adapted to perform
instructions stored in memory that may or may not be explicitly
shown. Various types of memory may be used, including volatile and
nonvolatile forms of memory. In various embodiments, instructions
are performed by the processor to perform a number of signal
processing tasks. In such embodiments, analog components may be in
communication with the processor to perform signal tasks, such as
microphone reception, or receiver sound embodiments (i.e., in
applications where such transducers are used). In various
embodiments, different realizations of the block diagrams,
circuits, and processes set forth herein may occur without
departing from the scope of the present subject matter.
[0034] The present subject matter is demonstrated for hearing
assistance devices, including hearing aids, including but not
limited to, behind-the-ear (BTE), receiver-in-canal (RIC), and
completely-in-the-canal (CIC) type hearing aids. It is understood
that behind-the-ear type hearing aids may include devices that
reside substantially behind the ear or over the ear. Such devices
may include hearing aids with receivers associated with the
electronics portion of the behind-the-ear device, or hearing aids
of the type having receivers in the ear canal of the user,
including but not limited to receiver-in-canal (RIC) or
receiver-in-the-ear (RITE) designs. The present subject matter can
also be used with in-the-ear (ITE) and in-the-canal (ITC) devices.
The present subject matter can also be used with wired or wireless
ear bud devices. The present subject matter can also be used in
hearing assistance devices generally, such as cochlear implant type
hearing devices and such as deep insertion devices having a
transducer, such as a receiver or microphone, whether custom
fitted, standard, open fitted, or occlusive fitted. It is
understood that other hearing assistance devices not expressly
stated herein may be used in conjunction with the present subject
matter.
[0035] This application is intended to cover adaptations or
variations of the present subject matter. It is to be understood
that the above description is intended to be illustrative, and not
restrictive. The scope of the present subject matter should be
determined with reference to the appended claims, along with the
full scope of legal equivalents to which such claims are
entitled.
[0036] The preceding detailed description of the present subject
matter refers to subject matter in the accompanying drawings that
show, by way of illustration, specific aspects and embodiments in
which the present subject matter may be practiced. These
embodiments are described in sufficient detail to enable those
skilled in the art to practice the present subject matter.
References to "an," "one," or "various" embodiments in this
disclosure are not necessarily to the same embodiment, and such
references contemplate more than one embodiment. The following
detailed description is demonstrative and not to be taken in a
limiting sense. The scope of the present subject matter is defined
by the appended claims, along with the full scope of legal
equivalents to which such claims are entitled.
* * * * *